How much of a reality for Abraham was God’s promise that his descendants would eventually own the land he was in? Very much so.

When it came time to find Isaac a wife, this promise was decisive. Abraham instructed his servant to NEVER take Isaac back to live amongst his relatives, even if the alternative was potentially no wife:

Genesis 24:6–8 Be careful never to take my son there [to live among your relatives in the land I came from]. For the Lord, the God of heaven, who took me from my father’s house and my native land, solemnly promised to give this land to my descendants. He will send his angel ahead of you, and he will see to it that you find a wife there for my son. If she is unwilling to come back with you, then you are free from this oath of mine. But under no circumstances are you to take my son there.

Abraham’s faith in this promise had already been counted to him as righteousness despite his many other failings. This faith now drove Abraham’s decisions, to the point of doing his best to keep Isaac away from any obvious possibility of accepting a lesser future.

Abraham’s faith was the evidence and substance of something he would not see in his lifetime.

Hebrews 11:1–2 Faith shows the reality of what we hope for; it is the evidence of things we cannot see. Through their faith, the people in days of old earned a good reputation.